I EXPECTED the SHOC to be scary, and I was not disappointed. The Strategic Health Operations Centre at the World Health Organization in Geneva is like a war room for diseases. From here, WHO leaders coordinate the response to pandemics and other global crises, surrounded by giant screens displaying video calls and the latest data. The last time it was called into serious action was in 2009, during the swine flu pandemic.

On a quiet day last month it seemed pretty benign, all blond wood, white walls and a few murmuring staff. Then I looked at a screen displaying Twitter feeds. One was on Syrian chemical weapons. Another was on a new Middle Eastern respiratory virus that has been compared to SARS. Four more were on H7N9, the deadly bird flu that emerged in March in China.

On another screen I could see a count of flu cases, now topping 100 – more in two months than the long-feared H5N1 bird flu racks up in two years. A third had a map of eastern China marking all known cases.

That was when the place began to feel scary. Epidemiologists love maps. If the WHO is mapping H7N9, I thought, it must be worried.

I was right. Last week WHO flu chief Keiji Fukuda went to China to assess the situation. At a press conference he described H7N9 as "an unusually dangerous virus for humans" and "definitely one of the most lethal influenza viruses we have seen so far". Fukuda is possibly the most measured, cautious scientist I have ever interviewed. This is serious.

H7N9 is a blend of bird flu viruses that has acquired a few mutations adapting it to infect people. It may occasionally pass from person to person via close contact, but is not yet spreading through the air like real human flu (at least not as New Scientist went to press). A few more mutations, though, might do it.

That would be very dangerous. Some claim that when bird flu adapts to mammals it invariably becomes less lethal, but that's simply not true. The 1918 flu pandemic, the worst in history, was a bird virus that adapted to mammals. Most human cases of the new strain are already very severe, and mammal-adapted H5N1 is no less deadly than natural H5N1.

The worry now is that as H7N9 sporadically infects people, it might be acquiring the mutations it needs to go on the rampage.

That's a good reason – alongside saving lives – to prevent human infections. But how? Fukuda's team says the virus has mostly infected chickens, ducks and pigeons in live poultry markets – cauldrons of viral evolution that flu virologists have warned about for years. Shutting these down helps: Shanghai closed its markets in early April and the spread of H7N9 slowed dramatically. Shutting the rest, all over east Asia, will be a tall order, but not as expensive as the viral risks of these markets, which also transmitted SARS and H5N1.

Killing infected poultry might help too, but could be difficult: unlike H5N1, the virus doesn't make chickens visibly ill. Poultry could be vaccinated, but that is risky: vaccinating them for H5N1 helped drive that virus's evolution. Moreover, Chinese researchers report that H7N9 is not found on poultry farms but only in markets. The real source might be city pigeons.

Maybe we'll get lucky and find that H7N9 can't acquire those mutations and cut loose in mammals. But if it can, killing and vaccinating poultry and preventing human infections won't stop a pandemic strain emerging. It will only slow it down.

When that happens, we will need vaccine. Oh dear. In the 2009 pandemic, vaccine arrived too late in the US to reach many people in the second wave – and many countries got none at all. Luckily, that flu was relatively mild. But that meant some governments didn't bother to buy pandemic vaccine, and some that did tried to sell it back, which did not encourage companies to tool up to make more. Since then there has only been a small increase in the global capacity to make vaccine.

Most vaccine is still made by growing flu virus laboriously in chicken eggs, which takes six months – if you're lucky. A few new factories that grow virus in cell cultures instead can expand production more readily, but are no quicker. And commercial factories won't switch from ordinary flu vaccine to H7N9 until a pandemic is imminent. By then it will be too late.

As for antiviral drugs, normal supply doesn't meet pandemic demand and cannot be ramped up quickly. The US ran short this year just from worse-than-usual winter flu.

There are several promising new technologies able to churn out vast quantities of pandemic vaccine quickly. But R&D funding has been limited. Only one is licensed, and for ordinary flu, not pandemic. It has one small manufacturing plant. None of the rest has even had a large-scale trial of its vaccines in people.

It could have been so different. After H5N1 appeared in 2004, or after the 2009 pandemic, we could have launched a major global programme to develop and test those technologies, modelled on the government-private sector partnerships that develop treatments for other unprofitable diseases such as TB. We didn't.

Maybe if we start now, and slow the virus down, we will have enough time. Chances are low, but if we don't even try they are zero.

As it stands, the WHO's top brass will watch any H7N9 pandemic unfold from the SHOC. Information will flood in; body counts will mount. Governments will be told that their demands for vaccines and drugs cannot be met. The SHOC will issue declarations, hold briefings, organise research, tell people to wash their hands and stay home. Mostly, though, it will just watch helplessly.

This article appeared in print under the headline "Sitting ducks for bird flu"

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